1. Field of the Invention
One embodiment of the present invention relates to a semiconductor device and a driving method thereof.
Note that one embodiment of the present invention is not limited to the above technical field. For example, one embodiment of the present invention relates to an object, a method, or a manufacturing method. Further, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. Thus, a semiconductor element such as a transistor or a diode and a semiconductor circuit are semiconductor devices. A display device, a light-emitting device, a lighting device, an electro-optical device, an electronic device, and the like may include a semiconductor element or a semiconductor circuit. Therefore, a display device, a light-emitting device, a lighting device, an electro-optical device, an electronic device, and the like include a semiconductor device in some cases.
2. Description of the Related Art
With the recent rapid spread of portable information terminals such as smartphones, improvement in performance of portable information terminals has progressed rapidly. Display devices used in portable information terminals are required to have high definition, high image quality, low power consumption, and the like.
An active-matrix display device where a transistor for driving a display element is provided in each pixel is known. For example, an active-matrix liquid crystal display device that includes a liquid crystal element as a display element, an active-matrix EL display device that includes an organic EL element as a display element, and the like are known. An active-matrix display device is easy to increase in display size or definition as compared to a simple-matrix display device, and is advantageous in reduction in power consumption and the like.
Along with an increase in the definition and image quality of display devices, digitally-driven display devices have attracted increased attention. A display device digitally driven converts a video signal supplied as a digital signal into an analog signal (greyscale signal) to display an image. In order to convert a digital signal into an analog signal, a DA converter or DAC (also referred to as a digital-to-analog converter) is used. Various types of DA converters (e.g., a pulse width modulation type, a resistor ladder type, a resistor string type, a capacitor array type, a delta-sigma type, and a current output type) are known. For example, a current output DA converter disclosed in Patent Document 1 is known.